Acidic fluid diet including liquid diets (such as fruit juice) and jelly drinks (herein meant to be jelly diets having gelled softly or partly enough to retain a fluidity) are commonly not required to be retort-sterilized. Accordingly, fluid diet sterilized by heating is put into a container in a heated state, and the container is sealed at its mouth, which is then turned upside down to sterilize the inner wall and mouth of the container by utilizing the heat of the fluid diet. This method is what is called hot packing, employed as a sterilization packing process.
Depending on products, another method is employed in which a container is filled with fluid diet and sealed and thereafter the whole container is immersed in hot water so as to be sterilized. Still another method is also employed in which a container is filled with fluid diet and sealed and thereafter hot water or steam is sprayed to the container so as to be sterilized.
Meanwhile, in recent years, as containers for such fluid diet, it has become popular to use those comprising a bag member formed of a flexible sheet, a straw-shaped mouth inserted to the bag member, and a cap thread-fitted to the tip of the mouth.
FIG. 8 illustrates an example of such containers, a container 11, which comprises a bag member 12 formed of a laminated sheet of plastic film and metal foil, a mouth 13 having the shape of a straw, inserted to one end of the bag member 12 and joined to the bag member 12 by, e.g., heat sealing, and a cap 14 thread-fitted to the projected end of the mouth 13.
This container 11 is so made up that the mouth 13 has an inner diameter of 1.5 cm or less, and usually 1 cm or less and the mouth 13 has a length L of 1 cm or more, and usually 2 cm or more. The mouth 13 and the cap 14 are made of a synthetic resin such as polyester.
In the case of this container 11, the container itself is comprised of the bag member 12, having a flexibility, and hence the mouth 13 can be used as a substitute for a straw to suck the inside fluid diet. Thus, such containers are going to be widely used for jelly drinks.
There is, however, a problem which has been found in the instance where the container 11 having a long and slender mouth 13 as shown in FIG. 8 is filled with the fluid diet by the conventional process, what is called hot packing. In such an instance, after the container is filled with a heated fluid diet, the container is turned upside down in order to sterilize the container up to the mouth 13, where the fluid diet can be flowed into the mouth 13 with difficulty, and, even when flowed into it, the temperature drops before the fluid diet reaches the tip of the mouth 13, so that the inner walls of the mouth 13 and cap 14 can not be well sterilized.
As a method to solve the above problem, one may contemplate filling the container 11 with the heated fluid diet and thereafter immersing the whole container 11 in hot water or the like to again heat it. This, however, results in excessive heating of the fluid diet held in the container to tend to cause deterioration of flavor in the case of fruit juice or the like and cause a decrease in jelly strength in the case of jelly drinks, bringing about the problem of a lowering of product quality.
One may also contemplate filling the container 11 with heated fluid diet and thereafter spraying hot water or hot steam to only the mouth 13 and cap 14 of the container 11. This, however, results in a great consumption of heat energy, and may make working atmosphere bad because of the hot steam hanging over surroundings, which may also adversely affect the surrounding equipment and may make the heating temperature of the mouth 13 and cap 14 non-uniform, bringing about the problem that no stable heat sterilization effect can be obtained.